Various electronic equipments exist capable of outputting a plurality of sounds, for example, the ring tone of a mobile phone, the audio sound in playing audio, and the TV sound in watching TV exist. Such electronic equipment has a function that controls the volume of each of the plurality of sounds, while the user of the electronic equipment controls the volume of them, thereby the voice output environment of the user adjusted electronic equipment can be set.
As to the conventional art, a device having such audio control function, is for example, an information terminal which can control the volume balance of the audio sound in playing audio and the telephone call sound through moving a mark in a displayed volume balance bar to the right and left (for example, refer to Patent Document 1). The volume bar indicates the ratio of the volume of the audio sound and the telephone call sound. In the information terminal, since the balance of the volume can be visually identified, the volume of the audio sound and the telephone call sound can be simply controlled.
Additionally, with the controlling of the volume of the whole 5.1 channel, the volume of the center channel (the channel outputting the voice of man such as the narration or the speech), a broadcasting receiving device including a function that can extract just the sound of the center channel from the sound of the whole channel for independently controlling is suggested (for example, refer to Patent Document 2).    Patent Document 1: JP-A-2003-258988    Patent Document 2: JP-A-2001-245237